1. Field of the Invention.
The invention concerns a video conference installation for a plurality of subscriber points, with each subscriber point having transmission and reception arrangements for audio signals (e.g., an electroacoustic converter) and image signals (e.g., television camera and video monitor). The subscriber points have access to a shared processing installation which is used to transmit the audio and video signals arriving from the subscriber points. The processing installation has individual subscriber units, each of which is permanently assigned at the beginning of the conference to any desired subscriber point participating in the conference, for the duration of the subscriber conference, and each individual subscriber unit is equipped with image memories with reading and writing devices which make the camera video signals of a full frame completely available, and multiplexers. The apparatus allows optional access to the video signals of all the cameras. The apparatus processes the audio and video signals to be transmitted to the individual subscriber points on the basis of control signals from these subscriber points in the individual subscriber units.
2. Prior Art.
A video conference installation of this general kind is already known. EP-OS No. 0 153 903 describes an information system for visual conferences which has a central visual conference unit equipped with image memories that performs the switching function between the sending and receiving devices for the audio and image signals. The technically relatively complex installations needed for this switching function, and for preparing the individual video signals to form individually constituted mixed images for all of the transmitting and receiving installations that can be connected, is required only in the central video conference unit and therefore exclusively in the context of the actual video conference traffic. Utilization of the central video conference unit makes it possible to implement video conferences along the lines of studio conferences as only one point-to-point connection at a time having bidirectional channels, with sufficient bandwidth for transferring video, audio and signalling information, being required. A conference director for video direction then becomes completely unnecessary, since direction can be performed individually at any time in the context of several predefined possible variations from each location, according to the party's own parameters and desires, with no repercussions on the other transmitting and receiving arrangements. A disadvantage of this known information system for video conferences is the provision of microphones, loudspeakers and special equipment with the selection, audio direction and video direction operating elements.